[DRBD-user] "Concurrent local write detected!"

Felix Frank ff at mpexnet.de
Mon Jan 3 09:22:23 CET 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

>> <snip>
>> But the result is undefined! What should DRBD write to the other member? The
>> result of the first or the second write?
>> You are using a tool that permits the execution of stupid I/O streams. Good
>> for stress testing, but not good for data integrity. If you want undefined
>> data on a DRBD pair, then disconnect before the I/O, do the undefined thing,
>> and upon reconnect DRBD will faithfully replicate the garbage. It will still
>> be  undefined stuff, but it will be identical undefined stuff.
> Are you seriously thinking that Unix doesn't allow two writes to the
> same LBA simultaneously?
> This is part of Unix file system semantics.
> A dead system is not the proper outcome.

Color me ignorant, but what have *file system* semantics got to do with
a block device?

But I concur, if at all possible, DRBD should probably have a way to
serialize writes in such circumstances.


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